Production of N,N-dichloro-terephthalamide and N,N-dichloro-isophthalamide

Abstract

Preparation of N,N'-dichloro-terephthalamide or N,N'-dichloro-isophthalamide by chlorination of an aqueous suspension of the corresponding terephthalamide or isophthalamide under acid conditions in which the dilution of the reaction mixture is sufficient to maintain the hydrogen chloride being produced as a by-product of the chlorination substantially completely dissolved in the reaction mixture up to the end of the reaction. The compound N,N'-dichloro-terephthalamide has been discovered to be a very stable mild oxidizing agent useful as an antiseptic. Both compounds obtained by the disclosed preparation are valuable intermediate compounds.

The invention is hereby claimed as follows: 
     
       1. A process for the production of N,N'-dichloro-terephthalamide or N,N'-dichloro-isophthalamide from the corresponding terephthalamide or isophthalamide as the initial phthalamide reactant, which process comprises: reacting chlorine at a temperature of about 0°C. to 100°C. with said phthalamide reactant suspended in a liquid reaction mixture which, over the course of the reaction, consists essentially of a dilute aqueous solution of a mineral acid, the dilution being such that all of the hydrogen chloride formed by the chlorination reaction remains substantially completely dissolved in the reaction mixture.   
     
     
       2. A process as claimed in claim 1 wherein the reaction is carried out at a pressure of about 1 to 20 atmospheres. 
     
     
       3. A process as claimed in claim 2 wherein the reaction temperature is about 0°C. to 60°C. 
     
     
       4. A process as claimed in claim 1 wherein the reaction is initiated in a neutral aqueous suspension of said phthalamide. 
     
     
       5. A process as claimed in claim 1 wherein the reaction is initiated in a dilute hydrochloric acid suspension of said phthalamide. 
     
     
       6. A process as claimed in claim 1 wherein the reaction is initiated in a dilute sulfuric acid suspension of said phthalamide. 
     
     
       7. A process as claimed in claim 1 wherein the amount of said initial phthalamide reactant is about 20 to 400 grams per liter of the aqueous reaction mixture. 
     
     
       8. A process as claimed in claim 7 carried out as a batch process over a period of about 2 to 60 minutes. 
     
     
       9. A process as claimed in claim 8 in which a uniform heterogeneous phase is maintained in the reaction mixture by thorough mixing.